For example, Patent Literature 1 discloses a semiconductor device including a semiconductor substrate on which a plurality of avalanche photodiodes that operate in a Geiger mode are provided and a mounting substrate on which a plurality of signal processing units that process an output signal from each avalanche photodiode are provided. In the semiconductor device disclosed in Patent Literature 1, a front surface side and a rear surface side of the semiconductor substrate are electrically connected to each other through a through hole formed in the semiconductor substrate.